We present results of a 45-participant laboratory study investigating the usability of tools to limit online behavioral advertising (OBA).We tested nine tools, including tools that block access to advertising websites, tools that set cookies indicating a user’s preference to opt out of OBA, and privacy tools that are built directly into web browsers. We interviewed participants about OBA, observed their behavior as they installed and used a privacy tool, and recorded their perceptions and attitudes about that tool. We found serious usability flaws in all nine tools we examined.

The online opt-out tools were challenging for users to understand and configure. Users tend to be unfamiliar with most advertising companies, and therefore are unable to make meaningful choices. Users liked the fact that the browsers we tested had built-in Do Not Track features, but were wary of whether advertising companies would respect this preference. Users struggled to install and configure blocking lists to make effective use of blocking tools. They often erroneously concluded the tool they were using was blocking OBA when they had not properly configured it to do so.